2 pair of 700 in my case too. I’ve got a CX bike not a gravel (Giant TCX Advanced Pro with 2x setup) but I use it as a gravel bike and my road bike. I prefer narrow tires on gravel so I use Pirelli Cinturato Gravel H 35mm on aluminium hand built wheels and Schwalbe Pro One 28mm on FFWD carbon ones. In my case it has a lot of sense. During my travels with bike I have a lot of problems with wheels and in this setup I have always spare pair I can change tires on them if I need it.